Timer switch apparatus

ABSTRACT

A timer switch including a plurality of separately depressible push button switches each electrically connected to a different RC timing circuit. Each timing circuit is connected in electrical parallel to an electrically energizable solenoid operatively attached to a release bar for releasing a depressed push button upon energization of the solenoid through the timing circuit associated with the depressed button.

1 TIMER SWITCH APPARATUS This is a continuation of application Ser. No.252,212, filed May It, 1972.

BACKGROUND OF THE INVENTION 1. Field of the Invention:

The present invention pertains to timer switch apparatus of the typehaving a plurality of depressible push button switches.

2. Cross Reference to Related Patents:

See my U.S. Pat. No. 3,325,609 entitled Timer Switch Controlled By PushButton and Motor Operated Cams which issued on June 13, 1967.

3. Background of the Prior Art:

Timer switches of the type having a plurality of depressible pushbuttons. each automatically releaseable after a different pre-determinedtime period find numerous applications. For example, such timer switchesare commonly utilized in conjunction with microwave ovens to provide ON"or HEAT" periods of various lengths. It is highly desirable, of course,that these switches are readily settable for various pre-determined timeperiods and are also relatively accurate.

Prior to the timer switch apparatus disclosed and claimed in myabove-mentioned U.S. Pat. No. 3,325,609, timer switches were eitherextremely complicated in design or relatively inaccurate. To providesimplicity of design yet relatively high accuracy, my previous timerswitch utilized a plurality of depressible push buttons eachindividually releaseable by means of a release bar operatively connectedto a plurality of adjustable motor driven cams. The cams were relativelyeasily adjustable sov as to allow variations in the length of theactuated period associated with each of the push buttons. Additionally,the locking arrangement provided to retain each of the push buttons in adepressed position was reliable over extended periods of utilization.However, the construction of this apparatus still necessitatedconsiderably higher manufacturing costs than desired as the overallreliability of the apparatus was dependent upon the quality of themotor, cams, and other components utilized to release the depressed pushbutton at the desired moment.

SUMMARY OF THE INVENTION The present invention represents an improvementon the timer switch apparatus disclosed and claimed in my prior U.S.Pat. No. 3,325,609. Broadly speaking, the present invention replaces themechanical timing mechanism of my previous invention with electronictiming means operating in conjunction with electrically energizablesolenoid means to release a depressed push button switch after apre-determined period of time.

More specifically, the present invention provides a plurality ofelectrical timing circuits (e.g. RC timing circuits) each associatedwith a different push button switch and each connected in electricalparallel to an electrically energizable solenoid. The solenoid is inturn operatively connected to releasable latch means for separatelysecuring the push buttons in a depressed or actuated position. Uponenergization of the solenoid through one of the timing circuits, thereleasable latch is moved between its push button securing position to apush button release position thereby opening the switch connected to theenergizing timing circuit.

As will become readily apparent from a reading of the DetailedDescription which follows, the present invention considerably simplifiesthe commercially available timer switch apparatus and, as a result,significantly reduces manufacturing costs. Further, the length of timewhich each push button is retained in its depressed position can bereadily varied (e.g. simply by changing the resistance in the associatedRC timing circuit). This significantly increases the flexibility of theswitching apparatus. In addition to the increased flexibility, thepresent apparatus has demonstrated greater reliability and repeatabilitythan the presently available timer switches. Finally, in the preferredembodiment the movement of a push button release bar is also utilized tosound an alarm bell thereby providing an audible indication that adepressed switch has been released and the ON period, of the switchingapparatus has terminated. This eliminates the need for additionalelectrical circuitry to provide an audible or visual alarm.

BRIEF DESCRIPTION OF THE DRAWINGS Referring now to the drawings whereinlike numerals represent, like elements of the invention throughout thevarious figures:

FIG. 1 is a view in top plan of the timer switch apparatus provided bythe present invention;

FIG. 2 is an enlarged sectional view as seen from the line 2-2 in FIG.1, parts thereof being broken away;

FIG. 3 is a sectional view as seen from the line 3-3 in FIG. 2, partsthereof being broken away;

FIG. 4 is a view in perspective of the contact carriage forming part ofeach depressible push button utilized in the present invention; v

FIG. 5 is a view in perspective of the sliding element of eachdepressible push button;

FIG. 6 is a perspective view of the release bar for latching andreleasing the depressed push button; and

FIG. 7 is an electrical schematic of the circuitry utilized to time therelease of a depressed push button.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the drawings, thenumeral 10 generally designates the timer switch apparatus provided bythe present invention. Switch apparatus 10 includes a plurality ofgenerally identical push button switches l2a-l2f which are mounted injuxtaposition in a generally U-shaped base member 14. As shown, basemember 14 includes an essentially solid outer or front wall 15 and arear wall formed by a plurality of spaced fingers or upright projections16. Base member 14 is attached to a chassis 17 by suitable means.

Since switches lM-lZf are generally identical, only a single switch(e.g. switch 12a) need be described in detail. Switch 12a includes acube-shaped button or knob 18 which is attached to a slideable shaft 20.Shaft 20 extends through a slot in the front wall 15 of U- shaped member14 and between two adjacent ones of the fingers 16 forming the rearwall. A compression spring 22 in engagement with front wall 15 ofU-shaped member 14 biases switch 12a outwardly to a nondepressedposition. A contact carriage 24 is fixedly attached to the slideableshaft 20 by suitable means (not shown) for movement between the frontand rear walls of member 14. The contact carriage 24 is formed from asuitable non-conducting material such as various plastics. A pair ofspring biased contact elements 25a and 25b are carried by contactcarriage 24 in an axially spaced relationship. Contact element 25a isslidingly engageable with a grouping of three spatially separatedstationary contact elements 26a, 26b, and 26c. Similarly, contactelement 25b is slidingly engageable with stationary contacts 27a, 27band 27c. Push buttons l2b-l2f are provided with similar carriages andcontact elements with the exception of push button 12f which includes athird sliding contact 250 mounted on carriage 24 for contacting agrouping of stationary contact elements 28a, 28b and 280. As explainedsubsequently in greater detail, contact element 25a engages the outertwo contact elements 26a and 26b in its non-depressed position andengages the inner two contact elements 26b and 26c when pushed inwardlyagainst the bias of spring 22 to its depressed position. Similarly,sliding contact 25b engages contact elements 27a and 26b in itsnon-depressed position and contact elements 27b and 27c in its depressedposition. Contact elements 26a-26c, 27a-27c and 28a-28c are mounted on aterminal or printed circuit board 29 which is attached to chassis l7.

Releaseable switch latching means in the form of an elongated releasebar 30, best seen in FIG. 6, having a plurality of similarslots 32axially spaced therealong. A plurality of upstanding shoulder portions34 are positioned along the front edge of the release bar 30 adjacent acorner of each of the slots 32. Each elongated slot 32 is of sufficientsize so as to receive a different one of the fingers 16 forming the rearwall of U-shaped member 14. The fingers 16 project through the slots 32so as to allow limited axial movement of the release bar 30 whilesubstantially preventing movement of bar 30 in the same direction as themovement of switches 12a-12f. With release bar 30 so positioned, each ofthe shoulders 34 is positioned adjacent a different one of the slideableshafts 20 of switches 12a-12f for the purpose subsequently described.

The slideable shaft 20 of switch 12a includes an offset or elevatedouter portion 20a. A finger portion 35 extends inwardly from outer shaftportion 20a into an elongated opening 36 in shaft 20. An outer end ofcompression spring 22 is coiled about finger portion 34 so as to urgebutton 12a outwardly as previously described.

Slideable shaft 20 further includes a rectangular opening 38 in theinnermost end thereof. A toothshaped member 40 projects into the opening38 and is positioned with respect to the adjacent shoulder 34 of releasebar 30 so that the shoulder is moved axially in a direction away fromthe member 40 as push button 12a is depressed. Upon the outermostextended point of tooth 40 passing shoulder 34, the release bar 30 thenmoves toward the tooth 40 positioning the shoulder 34 in the groovedefined by the tooth-shaped member 40. This prevents the slideable shaft20 from returning to its forward or non-depressed position upon theurging of compression spring 22. It should be noted that if one of theremaining switches 12b-l2f is now depressed (e.g. switch 12f as showndepressed in FIG. 3), the tooth shaped member 40 of the newly depressedswitch will cam the release bar 30 away from tooth 40 of depressedswitch l2a thereby releasing the slideable shaft 20 of switch 12a as thedepressed one of the other switches l2b-l2f is latched.

It should be additionally noted that, if desirable, apparatus can beutilized in conjunction with switches 12a-12f to prevent more than oneswitch from being simultaneously depressed. For a description of oneparticularly preferred form of such apparatus, see my US. Pat. No.3,325,609.

An electrically energizeable solenoid is mounted on chassis 17 andincludes a plunger element 51 which is attached to an end of release bar30 by a pin 52. When solenoid 50 is in a non-energized state, plungerelement 51 is urged outwardly by spring means within apparatus 10 (notshown) and, consequently, release bar 30 is normally biased in adirection away from solenoid 50. This results in tooth shaped member 40of the depressed one of the switches l2a-l2e (e. g. switch 12a) engaginga shoulder 34 of release bar 30 preventing the depressed switch fromreturning to its non-depressed position. When solenoid 50 is energized,plunger 51 is drawn inwardly causing release bar 30 to movelongitudinally toward solenoid 50. As this occurs, shoulder 34 is freedfrom the tooth shaped member 40 releasing depressed switch 12a to returnto its non-depressed position. As shown, the end of release bar 30opposite the end attached to solenoid 50 includes an upturned portion30a which is suitable for contacting a bell 55 mounted on chassis 17.Upon energization of solenoid 50, the upturned portion 30a of releasebar 30 is moved toward bell 55 contacting the lip thereof so as toprovide an audible indication that depressed switch 12a has beenreleased. Switches 12b-12f are similarly latched by bar 30 and releasedupon energization of solenoid 50.

Turning now to FIG. 7, the electrical timing circuitry for energizingsolenoid 50 and releasing the depressed one of the switches 12a-12f isillustrated. A pair of terminals and 61 are suitable for connecting to a115 volt AC power source (not shown); terminal 60 being positive andterminal 61 being neutral or ground. A lead 62 is connected to terminal60 and through a neon bulb 64 to terminal 260 of switch 12]". Whenswitches 12a-12f are in their de-energized position as schematicallyshown in solid lines in FIG. 7, terminal 260 of switch 12f is connectedto terminal 26a of each of the switches 12a-12f by contact element 25aextending between stationary contacts 26a and 26b of each of theswitches and a plurality of leads 65 connecting each of the terminals26b of switches 12a-12f to the terminal 26a of an adjacent one of theswitches. A lead 68 connects stationary contact 26b of switch 12a toterminal 61 and, thus, when the switches 12a-12f are all in theirde-energized position, a circuit is completed between terminals 60 and61 through neon bulb 64. This lights bulb 64 providing a visualindication that the apparatus is in its ready" state; i.e., that one ofthe switches 12a-12f can be depressed to provide current to the switchedload in the manner subsequently described.

A lead 70 is connected to terminal 60 and through a capacitor 72, adiode 73 and a resistor 74 to terminal 260 of switch 12a. A lead 79connects the contact element 260 of each of the remaining switches12b-l2f to contact 26c of switch 12a. An output terminal 75 suitable forconnecting to a switched load (e.g. a relay which energizes a voltagesupply to provide power to a microwave oven), is also connected toterminal 26c through a lead 76. A neon bulb 77 is connected to lead 76and to lead 62 through a lead 78 to provide a visual indication of acompleted circuit to the switched load (i.e., to indicate that switchingapparatus is in its OPERATE mode).

A lead 80 is connected to lead 70 between capacitor 72 and diode 73.Lead 80 is connected through a resistor 82 to a lead 83 which, in turn,connects each of the terminals 27c of switches 12a-12f in parallel toone another through resistors 85-90, respectively. As will subsequentlybe made apparent, each of the resistors 85-90 form the variableresistance portion of an RC timing circuit for determining the length oftime which the associated one of the switches 12a-12f remains depressed.Preferably, resistors 85-90 are readily removeable from the circuit soas to allow easy substitution thereof for varying the RC timing periods.In FIG. 1, it can be seen that resistors 85-90 are each slideablyremoveable from a pair of female terminals or receptacles mounted onprinted circuit board 29.

Lead 83 and resistors 85-90 are also connected to AC terminal 61 throughan SCR 91 and a Zener diode 92. As shown, the anode 93 of SCR 91 isconnected to a lead 94 and terminal 61 whereas the SCR cathode 95 isconnected to a lead 96 which is in turn connected to a lead 97 and theanode of the Zener diode 92. The lead 97 is connected to lead 80 betweenresistor 82 and common lead 83 through diode 92. A terminal 98 of lead97 is connectable to the switched load for external supply (i.e., ACneutral or ground) for allowing energization of solenoid 50, shownconnected between leads 70 and 97, and thus terminate the energizingpower supplied to the load upon the occurrence of a certain event (e.g.the opening of the door of a microwave oven). Capacitor 72, diode 73 andresistor 74 comprise a constant current supply for stabilizing thevoltage at Zener diode 92 reducing the effect of line variations.

As shown, terminal 28a of switch 12f is connected through a lead 100 toa potentiometer 102 in a lead 104. The potentiometer 102 is connectedthrough a resistor 105 to lead 97 and through a resistor 106 and commoncharging capacitor 108 to a lead 110. A resistor 112 is connected inparallel to resistors 102 and 105. Resistors 105 and 106 provide theproper biasing voltage levels at a transistor 118 subsequentlydescribed. Resistors 102, and 112 function as trimmer resistors tocompensate for variations in component and power levels in the RC timingcircuit.

The terminal 28b of switch 12f is connected to the base 120 of PNPtransistor 118 through a lead 121. The emitter 122 of transistor 118 isconnected through a lead 123 to the terminal 27b of switch 12f. Asshown, terminal 27b of switch 12f is connected in series to theterminals 27b of switches l2a-12e by a lead 124. Finally, the collector126 of transistor 120 is connected to lead 110 and through a neon bulb130 and a resistor 132 to the gate 135 of SCR 91. A resistor 138 isconnected between gate 135 and cathode 95 of SCR 91 to prevent theoccurrence of transient voltage spikes in the timing circuit. Finally, alead 140 connects lead 96 to lead 104 between resistor 106 and capacitor108.

Typical examples of component values for use in a timing circuit toenergize solenoid 50 utilizing a U5 volt AC power source are as follows:

COMPONENT VALUE Resistor 74 100 Ohms 82 4700 86 Selection variable. 87approximately 10,000 88 Ohms per each timing 89, second desired. 1021000 (potentiometer) 1800 106 12000 112 1000 132 100 138 470 Capacitor72 4.0-4.7 MFD 108 5.0 Diode lN5060 SCR S200lMS2 Zener Diode IN4763Transistor 2N5400 Neon Bulb 130 SAHB The operation of the preferredtiming circuitry can be explained as follows. With volts AC appliedacross terminals 60 and 61 and switches 12a-12f in their de-energizedposition (i.e., non-depressed position) neon bulb 64 is caused to glowin the manner previously described. Upon depression of one of theswitches l2a-12f(e.g. switch 12a) current flow through neon bulb 64 isterminated and the switchable load connected to terminal 75 is switchedon by the connection of terminal 75 to terminal 61 through switch 12a.This also results in the lighting of neon bulb 77 in the mannerpreviously described.

Upon depression of switch 120, sliding contact 25b engages terminals 27band 270 so as to provide a current path therethrough connecting ACterminal 60 to the emitter 122 of PNP transistor 120. This raises thepotential of emitter 122 relative to base switching PNP transistor 118into its conducting state. Upon this occurring, the current flow throughlead 110 charges capacitor 108 through resistors 102, 105, 106, 112 andthrough resistor 85 connected to depressed switch 120. Capacitor 108continues to charge at a rate determined by the resistance of resistor85 until it reaches the firing potential of neon bulb at which time bulb130 fires through the solenoid 50 energizing the solenoid.

Upon energization of solenoid 50, the release bar 30 is pulled towardsolenoid 50 causing the shoulder 34 to be released from the tooth shapedmember 40 of switch 12a. This allows the switch 12a to return to itsnondepressed position upon the urging of compression spring 22. Uponswitch 120 returning to its nondepressed position, the load is switchedto an of state and the apparatus is again "ready" for another cycle ofoperation. It should be understood that a different timing period isassociated with each of the push buttons 12a-12f due to the differencein the resistances of resistors 85-90, and thus the charging rate ofcapacitor 108.

Since my invention has been described in particular detail with respectto only a single preferred embodiment thereof, numerous modificationsthereto will be readily apparent to the artisan. For instance, withoutrequiring any inventive skill the polarity of the described timingcircuit can be reversed. Additionally, one of the push button switches12a-12f can have associated therewith a variable resistance to allowanalog selection of the desired RC timing period (eg resistor 90 ofswitch 12f as shown in dotted lines in FIG. 7). It is my intent to belimited solely by the spirit and scope of the appended claims.

What is claimed is:

l. Timer switch apparatus comprising:

a. a plurality of push button switches each movable between a depressedoperative position and a nondepressed position;

b. releasable switch latching means including an elongated release barpositioned generally perpendicular to the movement of said push buttonswitches and movable longitudinally between two limits of movement, saidswitch latching means having means for retaining each of said pushbutton switches in its depressed position at a position of said bar andsaid switch latching means releasing a depressed push button switch uponmovement of said bar a predetermined distance away from said positionand toward one of said limits;

electrically energizable solenoid means mechanically connected to saidrelease bar for longitudinally moving said bar said predetermineddistance upon energization of said solenoid means whereby to release adepressed push button switch;

d. electrical timing means electrically connected to said solenoid meansand including a plurality of electrical timing circuits, each circuitbeing electrically connected to a different one of a plurality of saidpush button switches for energizing said solenoid means and releasing adepressed push button switch after the passage of a predetermined amountof time; and

e. electrical control means connected to said solenoid means independentof said timing means for releasing a depressed push button switch uponthe occurrence of an event other than the passage of predeterminedamount of time.

2. The timer switch apparatus of claim 1 including a bell-like devicewherein said release bar includes a por- 3. Timer switch apparatuscomprising:

a. a'plurality of push button switches each movable between a depressedoperative position and a nondepressed position;

v b. releasable switch latching means including an elongated release barpositioned generally perpendicular to the movement of said push buttonswitches and movable longitudinally between two limits of movement, saidswitch latching means having means for retaining each of said pushbutton switches in its depressed position at a position of said bar andsaid switch latching means releasing a depressed push button switch uponmovement of said bar a predetermined distance away from said positionand toward one of said limits;

c. electrically energizable solenoid means mechanically connected tosaid release bar for longitudinally moving said bar in one direction ofmovement upon energization of said solenoid means;

d. means moving said latch bar in its other direction of movement upondeenergization of said solenoid means;

e. electrical timing means electrically connected to said solenoid meansand including a plurality of electrical timing circuits, each circuitbeing electrically connected to a different one of a plurality of saidpush button switches for changing the energization of said solenoidmeans to release a depressed push button switch after the passage of apredetermined amount of time; and

f. electrical control means connected to said solenoid means independentof said timing means for releasing a depressed push button switch uponthe occurrence of an event other than the passage of predeterminedamount of time.

1. Timer switch apparatus comprising: a. a plurality of push buttonswitches each movable between a depressed operative position and anon-depressed position; b. releasable switch latching means including anelongated release bar positioned generally perpendicular to the movementof said push button switches and movable longitudinally between twolimits of movement, said switch latching means having means forretaining each of said push button switches in its depressed position ata position of said bar and said switch latching means releasing adepressed push button switch upon movement of said bar a predetermineddistance away from said position and toward one of said limits; c.electrically energizable solenoid means mechanically connected to saidrelease bar for longitudinally moving said bar said predetermineddistance upon energization of said solenoid means whereby to release adepressed push button switch; d. electrical timing means electricallyconnected to said solenoid means and including a plurality of electricaltiming circuits, each circuit being electrically connected to adifferent one of a plurality of said push button switches for energizingsaid solenoid means and releasing a depressed push button switch afterthe passage of a predetermined amount of time; and e. electrical controlmeans connected to said solenoid means independent of said timing meansfor releasing a depressed push button switch upon the occurrence of anevent other than the passage of predetermined amount of time.
 2. Thetimer switch apparatus of claim 1 including a bell-like device whereinsaid release bar includes a portion thereof for engaging said bell-likedevice upon the energization of said solenoid means so as to provide anaudible indication of the release of a depressed one of said push buttonswitches.
 3. Timer switch apparatus comprising: a. a plurality of pushbutton switches each movable between a depressed operative position anda non-depressed position; b. releasable switch latching means includingan elongated release bar positioned generally perpendicular to themovement of said push button switches and movable longitudinally betweentWo limits of movement, said switch latching means having means forretaining each of said push button switches in its depressed position ata position of said bar and said switch latching means releasing adepressed push button switch upon movement of said bar a predetermineddistance away from said position and toward one of said limits; c.electrically energizable solenoid means mechanically connected to saidrelease bar for longitudinally moving said bar in one direction ofmovement upon energization of said solenoid means; d. means moving saidlatch bar in its other direction of movement upon deenergization of saidsolenoid means; e. electrical timing means electrically connected tosaid solenoid means and including a plurality of electrical timingcircuits, each circuit being electrically connected to a different oneof a plurality of said push button switches for changing theenergization of said solenoid means to release a depressed push buttonswitch after the passage of a predetermined amount of time; and f.electrical control means connected to said solenoid means independent ofsaid timing means for releasing a depressed push button switch upon theoccurrence of an event other than the passage of predetermined amount oftime.